Closed-loop control of a base XY stage with rotational degree-of-freedom for a high-speed ultra-accurate manufacturing system

Modeling and control of a high-speed ultra-accurate XY stage used in manufacturing systems is considered in this paper. The base XY stage is a two dimensional linear stepper (Sawyer) motor including a rotational (yaw) degree-of-freedom. Manufacturing systems based on Sawyer motors are widely used in wafer probing applications and in automated assembly. A Sawyer sensor is being integrated for measuring the motor´s position, velocity and yaw rotation for closed-loop control purposes on our testbed at the CRRL. Utilizing results on robust control of nonlinear systems, an adaptive current-level controller is designed for the motor that renders the closed-loop system robust to a variety of uncertainties and disturbances. A detailed model of the motor that takes into account the significant uncertainties of the motor is used in the control design. The tracking error is shown to asymptotically converge to the origin. Simulation studies are presented to validate the controller performance